The invention relates to a pressure cylinder with a tubular casing, in which are arranged a plurality of parallel, cylindrical, inner chambers with in each case a longitudinally directed slot and a piston longitudinally guided in each inner chamber. Each piston has a force removal extension projecting outwards through the associated slot, connected via a connecting device with the other force removal extensions, at least one inner chamber being frontally terminated and provided with inlets and outlets. The piston guided in said inner chamber a packing at either end and the elongated slot of said inner chamber is sealed from the inside by a sealing strip.
British Pat. No. 470,088 discloses such a pressure cylinder arrangement, in which a plurality of cylinders are juxtaposed and are reinforced by external reinforcing webs. This arrangement aims at preventing widening of the elongated slots. In the described construction, there are three such cylinders, whose force removal extensions between them form in each case an angle of 120.degree.. The force removal extension are connected to a saddle, which has an approximately V-shaped cross-section. A slide with wheels running in guide rails is used for guiding the force removal extensions and the saddle connected thereto.
In the case of rodless pressure cylinders with a single piston, it is known (German Offenlegungsschrift No. 3,124,915) to arrange two parallel guideways on either side of the elongated slot on the outside of the cylindrical tube and to provide the force transmission member with a bracket, which is supported against the guideways. However, this construction suffers from the disadvantage that the guideways are always open and can easily become dirty and that also during the movement of the piston in a widened area, considerable frictional forces occur, which must be overcome by applying additional pressure.
A similar arrangement is known from U.S. Pat. No. 2,473,430, where the force removal extension is provided with a bracket, which engages in a roughly U-shaped manner over the exterior of the casing and is slidingly fixed by its two ends to in each case one rod guided parallel to the cylindrical casing. The same disadvantages occur as with the arrangement according to Offenlegungsschrift No. 3,124,915.
In the case of pressure cylinders with a piston rod, it is known to arrange parallel pistons. However, in this case, the arrangement of several parallel cylinders cannot then contribute to ensuring a guidance of the outer end of the piston rod.